Scientists say they have made a significant leap towards creating a vaccine that would protect against every form of flu.
The influenza virus is a constantly shifting target so seasonal flu vaccines rapidly become useless and new ones are needed each year.
A team at Imperial College London say they have made a "blueprint" for a universal flu vaccine.
Their discovery is published in the journal Nature Medicine.
Influenza is able to change the proteins that protrude from the surface of the virus as readily as people change outfits. However, the material on the inside is common to many strains of flu. Vaccine researchers believe targeting the core of the virus may be the way to develop a universal vaccine.
Researchers then teased out the specific part of the immune system that offered some pandemic flu protection and which part of the virus it was attacking.
Prof Ajit Lalvani, who led the study, told the BBC: "It's a blueprint for a vaccine. We know the exact subgroup of the immune system and we've identified the key fragments in the internal core of the virus. These should be included in a vaccine.
"In truth, in this case it is about five years [away from a vaccine]. We have the know-how, we know what needs to be in the vaccine and we can just get on and do it."
'Long journey'This would be a distinct approach compared with other forms of vaccination, such as the MMR jab. These trigger the immune system to produce antibodies that can attack an invader.
The prize could be huge. Seasonal flu kills between 250,000 and 500,000 people each year and new pandemics have the potential to take doctors by surprise and kill large numbers of people.
The influenza virus is a constantly shifting target so seasonal flu vaccines rapidly become useless and new ones are needed each year.
A team at Imperial College London say they have made a "blueprint" for a universal flu vaccine.
Their discovery is published in the journal Nature Medicine.
Influenza is able to change the proteins that protrude from the surface of the virus as readily as people change outfits. However, the material on the inside is common to many strains of flu. Vaccine researchers believe targeting the core of the virus may be the way to develop a universal vaccine.
Researchers then teased out the specific part of the immune system that offered some pandemic flu protection and which part of the virus it was attacking.
Prof Ajit Lalvani, who led the study, told the BBC: "It's a blueprint for a vaccine. We know the exact subgroup of the immune system and we've identified the key fragments in the internal core of the virus. These should be included in a vaccine.
"In truth, in this case it is about five years [away from a vaccine]. We have the know-how, we know what needs to be in the vaccine and we can just get on and do it."
'Long journey'This would be a distinct approach compared with other forms of vaccination, such as the MMR jab. These trigger the immune system to produce antibodies that can attack an invader.
The prize could be huge. Seasonal flu kills between 250,000 and 500,000 people each year and new pandemics have the potential to take doctors by surprise and kill large numbers of people.